The U.S. ad market expanded more than 5% during the second quarter, despite “mass market weakness,” and declines in some major national media, according to a quarterly update released early this morning by Pivotal Research Group analyst Brian Wieser.

He notes that the market expansion continues to come primarily from digital media, as the national TV ad marketplace eroded 1% and other major media experienced “double digit declines.”

“Digital advertising captured more than all of the industry’s growth in the quarter, and marketers who are organized around digital media appear to be driving these trends,” Wieser writes, adding: “While the full year 2017 now looks set to grow between +4% to +5%, these advertising growth trends are not far removed from where our historical model predicts they should be.”

Wieser said the quarter’s expansion is “more notable” considering the relative tepid results reported by some of the biggest mass marketers.

Despite digital’s continuing expansion, Wieser wrote that the medium’s growth “must eventually plateau,” raising “significant implications” for its bellwether duopolists: Facebook and Google.